Pigmented powder paint suspensions (pigmented powder slurries), production method and utilization thereof

ABSTRACT

Pigmented powder coating suspensions (pigmented powder slurries) preparable by
     (1) mixing at least two liquid components comprising in each case at least one liquid starting product in a static mixer, to give a liquid,   (2) emulsifying the liquid (1) in an aqueous medium in a dispersing unit, to give an aqueous emulsion of liquid particles, and   (3) cooling the emulsion (2) so that a suspension of dimensionally stable particles is formed,
 
wherein said aqueous medium comprises the suspension of at least one pigment;
 
and also processes for preparing them and their use as coating materials, adhesives, and sealing compounds or to prepare such compositions.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Phase Application of Patent ApplicationPCT/EP02/05437 filed on 17 May 2002, which claims priority to DE 101 26653.7, filed on 1 Jun. 2001.

The present invention relates to novel pigmented powder coatingsuspensions (pigmented powder slurries), preparable by an emulsificationprocess. It also relates to a process for preparing novel pigmentedpowder slurries by emulsification. The present invention additionallyrelates to the use of the novel pigmented powder slurries as coatingmaterials, adhesives, and sealing compounds for coating, bonding, andsealing motor vehicle bodies and parts thereof, the interior andexterior of motor vehicles, the inside and outside of buildings, doors,windows, and furniture, and for coating, bonding, and sealing in thecontext of industrial coating, particularly of small parts, coils,packaging, containers, electrical components, and white goods.

Pigmented powder coating materials in the form of aqueous suspensions(pigmented powder slurries) which are substantially free from organicsolvents and may be processed using liquid coating technologies, andprocesses for preparing them by melt emulsification, are known from theGerman patent application DE 196 52 813 A1. In this known process, thebinders, the crosslinking agents, and any further additives are fed inthe form of viscous resin melts into the dispersing apparatus, in whichthey are dispersed finely in the liquid phase. Alternatively, beforetheir dispersing in the dispersing apparatus in the liquid state, theingredients may first of all be mixed homogeneously with one another andthen, in a second step, dispersed finely in the liquid phase.Thereafter, the resulting emulsion is converted by cooling into asuspension containing solid, finely divided particles. Toothed-ringdispersing units are included among the dispersing apparatus that may beused.

According to column 7 lines 4 to 9 of DE 196 52 813 A1, use may be madein aqueous medium as stabilizers, dispersants or emulsifiers ofshort-chain amphiphilic polyacrylates prepared from acrylic acid,ethylhexyl acrylate, hydroxyethyl acrylate and an anionic comonomer inlyotropic phase by means of transfer polymerization. The surface tensionof aqueous solutions of the emulsifiers at the critical micelleconcentration (CMC), however, is no more specified than is the precisecomposition of the aqueous media.

Details concerning the incorporation of the pigments into the pigmentedpowder slurries are not disclosed.

Powder slurries prepared by melt emulsification are also described inthe German patent applications DE 100 06 673.9 and DE 100 18 581.9,unpublished at the priority date of the present specification.

The melts of the starting products are mixed in a static mixer and theresulting melt is passed to a toothed-ring dispersing unit in which itis emulsified in an aqueous medium containing emulsifiers.

Emulsifiers used include nonionic emulsifiers such as alkoxylatedalkanols and polyols, phenols and alkylphenols, or anionic emulsifierssuch as alkali metal salts or ammonium salts of alkanecarboxylic acids,alkanesulfonic acids, and sulfo acids of alkoxylated alkanols andpolyols, phenols and alkylphenols in aqueous medium. The surface tensionof aqueous solutions of the emulsifiers at the critical micelleconcentration (CMC), however, is not specified.

Among the many additives mentioned, pigments and fillers are included.The additives may also be present in the aqueous medium, provided theyare suitable for that purpose in accordance with their customary andknown function. For the known powder slurries it is of advantage if, forexample, the thickeners and/or the emulsifiers are present in theaqueous medium, i.e., substantially outside the solid particles. The useof pigment pastes or pigment preparations as aqueous medium is notdescribed in the patent applications unpublished at the priority date ofthe present specification.

A process for preparing powder slurries by melt emulsification is alsoknown from the international patent application WO 97/45476.

According to page 13 lines 5 to 20 of the international patentapplication, emulsifiers are used in the process. In the case of anaqueous phase or an aqueous medium, polyethylene glycol or polyvinylalcohol is used. The key factor is that the emulsifiers have an anchorcomponent which links the emulsifiers to the melt by means of physicaladsorption or chemical reaction. Examples of suitable anchor componentsare polar (meth)acrylate copolymers or the corresponding groups. Thesurface tension of aqueous solutions of the emulsifiers at the criticalmicelle concentration (CMC), however, is not specified.

For the known process it is important that the starting products of thepowder slurries are melted in an extruder and mixed with one another.Still in the extruder, the resulting melt is mixed with water. Thepigments are incorporated by way of the melt of the starting materials.

A disadvantage of this known process is that the temperatures and theresidence times in the extruder must be set precisely in order toprevent premature crosslinking of binders and crosslinking agents. Thereis also a risk of damage to the pigments during incorporation in theextruder.

Another process for preparing powder slurries by melt emulsification isknown from the international patent application WO 98/45356.

In this case ionic and nonionic emulsifiers (surfactants) are used inaqueous medium. Ionic emulsifiers used include the in situ reactionproducts of the carboxyl-containing olefin copolymers used in theprocess with ammonium hydroxide, triethanolamine, morpholine, anddimethylethanolamine. Preferred non-ionic emulsifiers are alkylphenolthioxylates and ethylene oxide-propylene glycol copolymers. The surfacetension of aqueous solutions of the emulsifiers at the critical micelleconcentration (CMC), however, is not specified.

In this known process, too, the starting products are melted in anextruder and mixed with one another. The melt is subsequently introducedinto an autoclave, in which it is emulsified. The emulsions of themelted particles are thereafter stirred under pressure at temperaturesabove their melting point in order to make them spherical. According topage 4 lines 20 to 23 of the international patent application, at least30 seconds are required for this purpose.

A comparable process is disclosed by the American patent U.S. Pat. No.4,056,653 A. According to column 2 lines 6 to 9 of the patent, at least30 seconds are likewise required for said process step.

A disadvantage of this known process is that during the comparativelylong treatment time even slight changes in the process conditions may beaccompanied by unwanted agglomeration of the melted particles.Furthermore, the pigments are again incorporated into the melts of thebinders in the extruder, and here too risk being damaged.

The known processes described above for preparing powder slurries bymelt emulsification have the further disadvantage that the extrudersused as mixing equipment have a comparatively low efficiency, so that acomparatively high energy input is necessary in order to produce ahomogeneous melt. Moreover, the emulsifiers employed are only able toeffect adequate stabilization of either the emulsified melted particlesformed to start with or the suspended solid particles which result aftercooling of the emulsion, but not both simultaneously in a large enoughamount. With the known processes, therefore, there is the risk that theywill react adversely even to slight variations in the process conditionsand will not produce powder slurries that meet the specification.Moreover, the incorporation of the pigments into the pigmented powderslurries is ineffective or attended by risk of damage to said pigments.

The use of dispersions of copolymers preparable in aqueous media bysingle-stage or multistage free-radical copolymerization of

-   a) at least one olefinically unsaturated monomer and-   b) at least one olefinically unsaturated monomer different than the    olefinically unsaturated monomer (a) and of the general formula I    R¹R²C═CR³R⁴  (I)-    in which the radicals R¹, R², R³, and R⁴ each independently of one    another are hydrogen atoms or substituted or unsubstituted alkyl,    cycloalkyl, alkylcycloalkyl cycloalkylalkyl, aryl, alkylaryl,    cycloalkylaryl, arylalkyl or arylcycloalkyl radicals with the    proviso that at least two of the variables R¹, R², R³ and R⁴ are    substituted or unsubstituted aryl, arylalkyl or arylcycloalkyl    radicals, especially substituted or unsubstituted aryl radicals,    as binders in coating materials, especially aqueous basecoat    materials (cf. the German patent application DE 199 30 665 A1),    primer-surfacers and antistonechip primers (cf. the German patent    application DE 199 30 067 A1), and clearcoat materials (cf. the    German patent application DE 199 30 6.64 A1) is known. Their use as    stabilizers, emulsifiers or dispersants is not described in the    patent applications.

It is an object of the present invention to find novel pigmented powderslurries preparable by an emulsification process, simply, reliably,rapidly and reproducibly with short residence times in the plant inquestion, without the risk of damage to the pigments, said slurriesreliably meeting the given specifications.

It is a further object of the present invention to find a novel processfor preparing pigmented powder slurries by emulsification which nolonger has the disadvantages of the prior art but which instead rapidlyprovides on-specification pigmented powder slurries simply, reliably,and reproducibly with short residence times in the plant in question,without the risk of damage to the pigments.

The invention accordingly provides the novel pigmented powder coatingsuspensions (pigmented powder slurries) preparable by

-   (1) mixing at least two liquid components comprising in each case at    least one liquid starting product in a static mixer, to give a    liquid,-   (2) emulsifying the liquid (1) in an aqueous medium in a dispersing    unit, to give an aqueous emulsion of liquid particles, and-   (3) cooling the emulsion (2) so that a suspension of dimensionally    stable particles is formed,    wherein said aqueous medium comprises the suspension of at least one    pigment.

In the text below, the novel pigmented powder slurries are referred toas “powder slurries of the invention”.

The invention also provides the novel process for preparing pigmentedpowder coating suspensions (pigmented powder slurries) byemulsification, which involves

-   (1) mixing at least liquid components each comprising at least one    liquid starting product in a static mixer to give a liquid,-   (2) emulsifying the liquid (1) in a dispersing unit in an aqueous    medium, to give an aqueous emulsion of liquid particles, and-   (3) cooling the emulsion, so that a suspension of dimensionally    stable particles is formed,    wherein said aqueous medium comprises the suspension of at least one    pigment.

In the text below, the novel process for preparing pigmented powdercoating suspensions (pigmented powder slurries) by melt emulsificationis referred to as the “process of the invention”.

Further subject matter of the invention, processes and uses will emergefrom the description.

In the light of the prior art it was surprising and unforeseeable forthe skilled worker that the object on which the present invention wasbased could be achieved by means of the process of the invention and thepowder slurries of the invention. More surprising still was that it wasthe copolymers of the monomers (a) and (b), hitherto used only asbinders, that had the properties required for them to be considered forthe process of the invention. Surprising not least was the fact that,for a comparatively low energy input and very short residence times, theprocess of the invention could give on-specification powder slurries ofthe invention with tailorable particle sizes and particle sizedistributions even without aftertreatment of the emulsified meltedparticles. Owing to the extremely gentle incorporation technique thereis also no damage to the pigments, which is why, for example, thecoatings produced from the powder slurries of the invention, even whenthey have a significantly lower pigment content, had an excellent visualappearance. Moreover, the powder slurries of the invention enabledreliable reproduction of the shades of the coatings. A particularsurprise, however, was that it was possible to increase the stability ofpowder slurries by means of the process of the invention.

The starting products used in the process of the invention for preparingthe powder slurries of the invention are selected with a view to thedesired composition and the curing mechanism of the powder slurries ofthe invention.

The powder slurries of the invention may be physically curing.

In the context of the present invention the term “physical curing”denotes the curing of a layer of particles of the powder slurries of theinvention by filming, with linking within the coating taking place bylooping of the polymer molecules of the binders (regarding the term cf.Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart,N.Y., 1998, “binders”, pages 73 and 74). Or else filming takes place byway of the coalescence of binder particles (cf. Römpp Lexikon Lacke undDruckfarben, Georg Thieme Verlag, Stuttgart, N.Y., 1998, “curing”, pages274 and 275). Normally, no crosslinking agents are required for thispurpose if desired, physical curing may be assisted by atmosphericoxygen, by heat, or by exposure to actinic radiation.

The powder slurries of the invention may be thermally curable. In thiscase they may be self-crosslinking or externally crosslinking.

In the context of the present invention the term “self-crosslinking”denotes the capacity of a binder to enter into crosslinking reactionswith itself. A prerequisite for this is that the binders already containboth kinds of complementary reactive functional groups which arenecessary for crosslinking. Externally crosslinking, on the other hand,is a term used to refer to those coating materials in which one kind ofthe complementary reactive functional groups is present in the binderand the other kind is present in a curing agent or crosslinking agent.For further details, refer to Römpp Lexikon Lacke und Druckfarben, GeorgThieme Verlag, Stuttgart, N.Y., 1998, “curing”, pages 274 to 276,especially page 275 bottom).

The powder slurries of the invention may be curable with actinicradiation.

In this case curing takes place by way of groups containing bonds whichcan be activated with actinic radiation. In the context of the presentinvention, actinic radiation means electromagnetic radiation, such asvisible light, UV radiation or X-rays, especially UV radiation, andcorpuscular radiation such as electron beams.

The powder slurries of the invention may be curable thermally and withactinic radiation.

Where thermal curing and curing with actinic light are employed togetherfor one powder slurry, the terms “dual cure” and “dual-cure powderslurry” are also used.

The powder slurries of the invention are preferably one-component (1K)systems.

In the context of the present invention, one-component (1K) systems arepowder slurries which cure thermally or both thermally and with actinicradiation and in which the binder and the crosslinking agent are presentalongside one another in the particles. A prerequisite for this is thatthe two constituents crosslink with one another only at relatively hightemperatures and/or on exposure to actinic radiation.

The amount of dimensionally stable particles in the powder slurries ofthe invention may vary very widely and is guided by the requirements ofeach individual case. It is preferably from 5.0 to 60, more preferablyfrom 10 to 55, with particular preference from 15 to 50, with veryparticular preference from 20 to 45, and in particular from 25 to 40% byweight, based in each case on the total amount of the powder slurry ofthe invention.

Similarly, the average particle size of the dimensionally stableparticles of the powder slurries of the invention may vary widely. It ispreferably between 0.1 and 100, more preferably between 0.2 and 80, withparticular preference between 0.3 and 60, with very particularpreference between 0.4 and 40, and in particular from 0.5 to 20 μm. Forespecially demanding end uses such as automotive OEM finishing, particlesizes of from 1 to 10 μm are especially advantageous.

In the context of the present invention, “dimensionally stable” meansthat under the customary and known conditions of the storage andapplication of powder coating suspensions the particles undergo littleif any agglomeration and/or breakdown into smaller particles but insteadsubstantially retain their original form even under the influence ofshear forces. The particles may be highly viscous and/or solid.Preferably, the dimensionally stable particles are solid.

The powder slurries of the invention are preferably free from volatileorganic compounds (VOCs), especially from organic solvents (cosolvents).In the context of the present invention this means that they have aresidual VOC content of <1% by weight, preferably <0.5% by weight, andwith particular preference <0.2% by weight. In accordance with theinvention it is of very particular advantage if the residual content issituated below the gas-chromatographic detection limit.

The process of the invention starts with the preparation of at least twoliquid components comprising at least one liquid starting product of thepowder slurries of the invention. The starting products may already beliquid at room temperature or may melt only at higher temperatures. Thecritical factor is that the starting products are liquid at the processtemperatures employed. Preferably, the starting products are solid atroom temperature.

The two liquid components may further comprise at least one additivewhich is not liquid at the process temperatures employed. However, anonliquid additive of this kind must be capable of homogeneousdistribution in the liquid components and must not disrupt the mixingprocesses in the static mixer or in the dispersing unit.

Preferably, one of the liquid components comprises the melt of at leastone of the binders described below. The binder melt may further compriseat least one of the additives described below. Preferably, theseadditives are meltable at the temperatures employed or are present inhomogeneous distribution in the melt.

Where the process of the invention is used to prepare powder slurries ofthe invention which cure physically or are curable with actinicradiation, at least one of the further liquid components or the furtherliquid components preferably comprise the melt of at least one of theadditives described below.

Where the process of the invention is used to prepare powder slurries ofthe invention which are curable thermally or both thermally and withactinic radiation, at least one of the further liquid components or thefurther liquid component preferably comprises the melt of at least oneof the crosslinking agents described below.

The preparation of the liquid components has no special features interms of its method but instead takes place using the customary andknown techniques and apparatus for preparing liquids, especially melts,such as extruders, stirred tanks, Taylor reactors, tube reactors, loopreactors, etc. The starting products, especially the binders, may beprepared continuously in such apparatus and discharged continuously as aliquid or melt.

In the liquefication or melting operation the process temperatures arechosen so as not to exceed the decomposition temperature of the startingproduct which decomposes the most readily. Preference is given toemploying melt temperatures of from 50 to 250, preferably from 60 to220, with particular preference from 70 to 200, with very particularpreference from 80 to 190, and in particular from 90 to 180° C.

Preferably, the liquid components each have process temperatures sosituated that during the mixing operation one liquid component is notcooled by the other to such an extent that solid agglomerates areformed. On the other hand, the process temperatures of the liquidcomponents must not be chosen to be so high that one liquid component isheated by the other to such an extent that, for example, decompositionreactions occur. With particular preference, the liquid components havethe same or approximately the same process temperature during the mixingoperation.

In the process of the invention the liquid components are first of allsupplied in the desired proportion to a customary and known staticmixer, and homogenized. Examples of suitable mixers are those of theSulzer type, sold by Sulzer Chemtech GmbH.

The residence times of the liquid components or unified liquid in thestatic mixer are preferably from 0.5 to 20, more preferably from 1 to18, with particular preference from 1.5 to 16, with very particularpreference from 1.5 to 15, and in particular from 1.5 to 10 seconds.

The liquid is subsequently supplied to the dispersing unit in which itis emulsified in an aqueous medium to give an aqueous emulsion of meltedparticles.

In accordance with the invention, the aqueous medium comprises thesuspension of at least one pigment.

Depending on the intended use of the powder slurries of the invention,use may be made of color and/or effect pigments, fluorescent pigments,electrically conductive and/or magnetically shielding pigments, metalpowders, organic and inorganic, transparent or opaque fillers, and/ornanoparticles (“pigments” collectively below).

The pigment content of the aqueous medium may vary very widely and isguided by the optical, mechanical, electrical and magnetic effects whichit is intended the products—especially the coatings, adhesives, andsealants—produced from the powder slurries of the invention should have,and by the dispersibility of the pigments. The pigments are preferablyused in an amount of from 1 to 90, more preferably from 2 to 85, withparticular preference from 3 to 80, with very particular preference from4 to 75, and in particular from 5 to 70% by weight, based in each caseon the aqueous medium.

In the process of the invention the pigments are preferably dispersed inthe form of pigment pastes or pigment preparations (cf. Römpp LexikonLacke und Druckfarben, Georg Thieme Verlag, Stuttgart, N.Y., 1998,“pigment preparations”, page 452) into the aqueous media.

Examples of suitable effect pigments are metal flake pigments such ascommercially customary aluminum bronzes, aluminum bronzes chromated inaccordance with DE 36 36 183 A1, and commercially customary stainlesssteel bronzes, and also nonmetallic effect pigments, such as pearlescentpigments and interference pigments, platelet-shaped effect pigmentsbased on iron oxide, which has a shade ranging from pink to brownishred, liquid-crystalline effect pigments. For further details, referenceis made to Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag,1998, page 176, “effect pigments” and pages 380 and 381, “metaloxide-mica pigments” to “metal pigments”, and to the patent applicationsand patents DE 36 36 156 A1, DE 37 18 446 A1, DE 37 19.804 A1, DE 39 30601 A1, EP 0 068 311 A1, EP 0 264 843 A1, EP 0 265 820 A1, EP 0 283 852A1, EP 0 293 746 A1, EP 0 417 567 A1, U.S. Pat. No. 4,828,826 A, andU.S. Pat. No. 5,244,649 A.

Examples of suitable inorganic color pigments are white pigments such astitanium dioxide, zinc white, zinc sulfide or lithopones; black pigmentssuch as carbon black, iron manganese black or spinel black; chromaticpigments such as chromium oxide, chromium oxide hydrate green, cobaltgreen or ultramarine green, cobalt blue, ultramarine blue or manganeseblue, ultramarine violet or cobalt violet and manganese violet, red ironoxide, cadmium sulfoselenide, molybdate red or ultramarine red; browniron oxide, mixed brown, spinel phases and corundum phases or chromeorange; or yellow iron oxide, nickel titanium yellow, chrome titaniumyellow, cadmium sulfide, cadmium zinc sulfide, chrome yellow or bismuthvanadate.

Examples of suitable organic color pigments are monoazo pigments, disazopigments, anthraquinone pigments, benzimidazole pigments, quinacridonepigments, quinophthalone pigments, diketopyrrolopyrrol pigments,dioxazine pigments, indanthrone pigments, isoindoline pigments,isoindolinone pigments, azomethine pigments, thioindigo pigments, metalcomplex pigments, perinone pigments, perylene pigments, phthalocyaninepigments or aniline black.

For further details, reference is made to Römpp Lexikon Lacke undDruckfarben, Georg Thieme Verlag, 1998, pages 180 and 181, “iron bluepigments” to “black iron oxide”, pages 451 to 453, “pigments” to“pigment volume concentration”, page 563, “thioindigo pigments”, page567, “titanium dioxide pigments”, pages 400 and 467, “naturallyoccurring pigments”, page 459 “polycyclic pigments”, page 52,“azomethine pigments”, “azo pigments”, and page 379, “metal complexpigments”.

Examples of (daylight-)fluorescent pigments are bis(azomethine)pigments.

Examples of suitable electrically conductive pigments are titaniumdioxide/tin oxide pigments.

Examples of magnetically shielding pigments are pigments based on ironoxides or chromium dioxide.

Examples of suitable metal powders are powders of metals and metalalloys comprising aluminum, zinc, copper, bronze or brass.

Examples of suitable organic and inorganic fillers are chalk, calciumsulfates, barium sulfate, silicates such as talc, mica or kaolin,silicas, oxides such as aluminum hydroxide or magnesium hydroxide, ororganic fillers such as polymer powders, especially of polyacrylonitrileor polyamide. For further details, reference is made to Römpp LexikonLacke und Druckfarben, Georg Thieme Verlag, 1998, pages 250 ff.,“fillers”.

Preference is given to employing mica and talc when the intention is toimprove the scratch resistance of the coatings produced from the powderslurries of the invention.

Moreover, it is advantageous to use mixtures of platelet-shapedinorganic fillers such as talc or mica and non-platelet-shaped inorganicfillers such as chalk, dolomite, calcium sulfates or barium sulfate,since by this means the viscosity and rheology may be adjusted veryeffectively.

Examples of suitable transparent fillers are those based on silica,alumina or zirconium oxide.

Suitable nanoparticles are selected from the group consisting ofhydrophilic and hydrophobic, especially hydrophilic, nanoparticles basedon silica, alumina, zinc oxide, zirconium oxide, and the polyacids andheteropoly acids of transition metals, preferably of molybdenum andtungsten, having a primary particle size >50 nm, preferably from 5 to 50nm, in particular from 10 to 30 nm. Preferably, the hydrophilicnanoparticles have no flatting effect. Particular preference is given tousing nanoparticles based on silica.

Very particular preference is given to using hydrophilic pyrogenicsilicas whose agglomerates and aggregates have a catenated structure,and which are preparable by the flame hydrolysis of silicontetrachloride in an oxyhydrogen flame. They are sold, for example, byDegussa under the brand name Aerosil®. Very particular preference isalso given to precipitated waterglasses, such as nanohectorites, whichare sold, for example, by Südchemie under the brand name Optigel® or byLaporte under the brand name Laponite®.

The aqueous medium to be used according to the invention may includeminor amounts of the below-detailed additives and/or organic solventsand/or other dissolved solid, liquid or gaseous organic and/or inorganicsubstances of low and/or high molecular mass, provided they do notadversely affect the emulsification by, for example, causing the liquidparticles to agglomerate, but instead contribute to stabilizing theemulsions of the liquid particles and of the powder slurries of theinvention. Examples of suitable additives of this type are thickeners oremulsifiers, especially emulsifiers. The term “minor amount” means anamount which does not remove the aqueous character of the aqueousmedium.

Suitable emulsifiers are the customary and known emulsifiers asdescribed, for example, in the patent applications cited at the outset.

For the preparation of the powder slurries of the invention it ispreferred to use an emulsifier whose aqueous solution at the criticalmicelle concentration (CMC) has a surface tension >30, preferably >35,and in particular >40 mN/m.

In the context of the present invention, the critical micelleconcentration (CMC) is the characteristic concentration at which above acertain temperature (the Krafft point) micelles form from surfactantmolecules in aqueous solutions (cf. Römpp-Chemie-Lexikon, Georg ThiemeVerlag, Stuttgart, N.Y., 9th edition, 1991, volume 4, pages 2769 and2770, “micelles”).

Accordingly, emulsifiers suitable for preparing the powder slurries ofthe invention are all ionic and nonionic emulsifiers which meet thiscondition.

Particularly preferred emulsifiers used are copolymers preparable bysingle-stage or multistage, especially single-stage, free-radical,especially controlled free-radical, copolymerization of

-   (a) at least one olefinically unsaturated monomer and-   (b) at least one olefinically unsaturated monomer different than the    olefinically unsaturated monomer (a) and of the general formula I    R¹R²C═CR³R⁴  (I),-    in which the radicals R¹, R², R³ and R⁴ each independently of one    another are hydrogen atoms or substituted or unsubstituted alkyl,    cycloalkyl, alkylcycloalkyl, cycloalkylalkyl, aryl, alkylaryl,    cycloalkylaryl, arylalkyl or arylcycloalkyl radicals, with the    proviso that at least two of the variables R¹, R², R³ and R⁴ are    substituted or unsubstituted aryl, arylalkyl or arylcycloalkyl    radicals, especially substituted or unsubstituted aryl radicals; in    an aqueous medium.

Examples of suitable monomers (a) are

-   (a1) substantially acid-group-free (meth)acrylic esters such as    (meth)acrylic alkyl or cycloalkyl esters having up to 20 carbon    atoms in the alkyl radical, especially methyl, ethyl, propyl,    n-butyl, sec-butyl, tert-butyl, hexyl, ethylhexyl, stearyl and    lauryl acrylate or methacrylate; cycloaliphatic (meth)acrylic    esters, especially cyclohexyl, isobornyl, dicyclopentadienyl,    octahydro-4,7-methano-1H-indenemethanol acrylate or    tert-butylcyclohexyl (meth)acrylate; (meth)acrylic oxaalkyl esters    or oxacycloalkyl esters such as ethyltriglycol (meth)acrylate and    methoxyoligoglycol (meth)acrylate having a molecular weight Mn of    preferably 550, or other ethoxylated and/or propoxylated    hydroxyl-free (meth)acrylic acid derivatives. These may contain    minor amounts of (meth)acrylic alkyl or cycloalkyl esters of higher    functionality, such as the di(meth)acrylates of ethylene glycol,    propylene glycol, diethylene glycol, dipropylene glycol, butylene    glycol, 1,5-pentanediol, 1,6-hexanediol,    octahydro-4,7-methano-1H-indenedimethanol or 1,2-, 1,3- or    1,4-cyclohexanediol; trimethylolpropane di- or tri(meth)acrylate; or    pentaerythritol di-, tri- or tetra(meth)acrylate. For the purposes    of the present invention, minor amounts of monomers of higher    functionality in this case are to be understood as amounts which do    not lead to crosslinking or gelling of the copolymers.-   (a2) Monomers which carry per molecule at least one hydroxyl group,    amino group, alkoxymethylamino group or imino group and are    substantially free from acid groups, such as hydroxyalkyl esters of    acrylic acid, methacrylic acid or another alpha,beta-olefinically    unsaturated carboxylic acid, which derive from an alkylene glycol    esterified with the acid, or which are obtainable by reacting the    alpha,beta-olefinically unsaturated carboxylic acid with an alkylene    oxide, especially hydroxyalkyl esters of acrylic acid, methacrylic    acid, ethacrylic acid, crotonic acid, maleic acid, fumaric acid or    itaconic acid in which the hydroxyalkyl group contains up to 20    carbon atoms, such as 2-hydroxyethyl, 2-hydroxypropyl,    3-hydroxypropyl, 3-hydroxybutyl, 4-hydroxybutyl acrylate,    methacrylate, ethacrylate, crotonate, maleate, fumarate or    itaconate; or hydroxycycloalkyl esters such as    1,4-bis(hydroxymethyl)cyclohexane,    octahydro-4,7-methano-1H-indenedimethanol or methylpropanediol    monoacrylate, monomethacrylate, monoethacrylate, monocrotonate,    monomaleate, monofumarate or monoitaconate; or reaction products of    cyclic esters, such as epsilon-caprolactone, for example, and these    hydroxyalkyl or hydroxycycloalkyl esters; or olefinically    unsaturated alcohols such as allyl alcohol or polyols such as    trimethylolpropane monoallyl or diallyl ether or pentaerythritol    monoallyl, diallyl or triallyl ether (as far as these monomers (a2)    of higher functionality are concerned, the comments made above    relating to the monomers (a1) of higher functionality apply    analogously); N,N-dimethylaminoethyl acrylate, N,N-diethylaminoethyl    methacrylate, allylamine or N-methyliminoethyl acrylate or    N,N-di(methoxymethyl)aminoethyl acrylate and methacrylate or    N,N-di(butoxymethyl)aminopropyl acrylate and methacrylate.-   (a3) Monomers which carry per molecule at least one acid group which    can be converted to the corresponding acid anion group, such as    acrylic acid, beta-carboxyethyl acrylate, methacrylic acid,    ethacrylic acid, crotonic acid, maleic acid, fumaric acid or    itaconic acid; olefinically unsaturated sulfonic or phosphonic acids    or their partial esters; or mono(meth)acryloyloxyethyl maleate,    succinate or phthalate.-   (a4) Vinyl esters of alpha-branched monocarboxylic acids having 5 to    18 carbon atoms in the molecule. The branched monocarboxylic acids    can be obtained by reacting formic acid or carbon monoxide and water    with olefins in the presence of a liquid, strongly acidic catalyst;    the olefins may be cracking products of paraffinic hydrocarbons,    such as mineral oil fractions, and may comprise both branched and    straight-chain acyclic and/or cycloaliphatic olefins. The reaction    of such olefins with formic acid or, respectively, with carbon    monoxide and water produces a mixture of carboxylic acids in which    the carboxyl groups are located predominantly on a quaternary carbon    atom. Examples of other olefinic starting materials are propylene    trimer, propylene tetramer and diisobutylene. Alternatively, the    vinyl esters (a4) may be prepared in a conventional manner from the    acids, by reacting, for example, the acid with acetylene. Particular    preference, owing to their ready availability, is given to using    vinyl esters of saturated aliphatic monocarboxylic acids having 9 to    11 carbon atoms that are branched on the alpha carbon atom, but    especially Versatic® acids.-   (a5) Reaction products of acrylic acid and/or methacrylic acid with    the glycidyl ester of an alpha-branched monocarboxylic acid having 5    to 18 carbon atoms per molecule, especially a Versatic® acid, or,    instead of the reaction product, an equivalent amount of acrylic    acid and/or methacrylic acid which is then reacted during or after    the polymerization reaction with the glycidyl ester of an    alpha-branched monocarboxylic acid having 5 to 18 carbon atoms per    molecule, especially a Versatic® acid.-   (a6) Cyclic and/or acyclic olefins such as ethylene, propylene,    1-butene, 1-pentene, 1-hexene, cyclohexene, cyclopentene,    norbornene, butadiene, isoprene, cyclopentadiene and/or    dicyclopentadiene.-   (a7) (Meth)acrylamides such as (meth)acrylamide, N-methyl-,    N,N-dimethyl-, N-ethyl-, N,N-diethyl-, N-propyl-, N,N-dipropyl-,    N-butyl-, N,N-dibutyl-, N-cyclohexyl-, N,N-cyclohexylmethyl- and/or    N-methylol-, N,N-dimethylol-, N-methoxymethyl-,    N,N-di(methoxymethyl)-, N-ethoxymethyl- and/or    N,N-di(ethoxyethyl)-(meth)acrylamide. Monomers of the last-mentioned    kind are used in particular to prepare self-crosslinking binders    (A).-   (a8) Monomers containing epoxide groups, such as the glycidyl ester    of acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid,    maleic acid, fumaric acid and/or itaconic acid.-   (a9) Vinylaromatic hydrocarbons such as styrene,    alpha-alkylstyrenes, especially alpha-methylstyrene, and/or    vinyltoluene; vinylbenzoic acid (all isomers),    N,N-diethylaminostyrene (all isomers), alpha-methylvinylbenzoic acid    (all isomers), N,N-diethylamino-alpha-methylstyrene (all isomers)    and/or p-vinylbenzenesulfonic acid.-   (a10) Nitriles such as acrylonitrile and/or methacrylonitrile.-   (a11) Vinyl compounds, especially vinyl halides and/or vinylidene    dihalides such as vinyl chloride, vinyl fluoride, vinylidene    dichloride or vinylidene difluoride; N-vinylamides such as    vinyl-N-methylformamide, N-vinylcaprolactam, 1-vinylimidazole or    N-vinylpyrrolidone; vinyl ethers such as ethyl vinyl ether, n-propyl    vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl    vinyl ether and/or vinyl cyclohexyl ether; and/or vinyl esters such    as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate    and/or the vinyl ester of 2-methyl-2-ethylheptanoic acid.-   (a12) Allyl compounds, especially allyl ethers and allyl esters such    as allyl methyl, ethyl, propyl or butyl ether or allyl acetate,    propionate or butyrate.-   (a13) Polysiloxane macromonomers having a number-average molecular    weight Mn of from 1000 to 40,000 and having on average from 0.5 to    2.5 olefinically unsaturated double bonds per molecule; especially    polysiloxane macromonomers having a number-average molecular weight    Mn of from 2000 to 20,000, with particular preference from 2500 to    10,000 and, in particular, from 3000 to 7000 and having on average    from 0.5 to 2.5, preferably from 0.5 to 1.5, olefinically    unsaturated double bonds per molecule, as are described in DE-A-38    07 571 on pages 5 to 7, in DE-A-37 06 095 in columns 3 to 7, in    EP-B-0 358 153 on pages 3 to 6, in U.S. Pat. No. 4,754,014 in    columns 5 to 9, in DE-A-44 21 823 or in the international patent    application WO 92/22615 on page 12 line 18 to page 18 line 10.-   (a14) Acryloxysilane-containing vinyl monomers, preparable by    reacting hydroxy-functional silanes with epichlorohydrin and then    reacting the reaction product with (meth)acrylic acid and/or with    hydroxyalkyl and/or hydroxycycloalkyl esters of (meth)acrylic acid    (cf. monomers a2).

Each of the abovementioned monomers (a1) to (a14) may be polymerized ontheir own with the monomers (b). In accordance with the invention,however, it is advantageous to use at least two monomers (a), inparticular at least one monomer (a1) and at least one monomer (a3),since by this means it is possible to vary the profile of properties ofthe resulting copolymers very widely, in a particularly advantageousmanner, and to tailor said profile of properties to the particularprocess of the invention. In particular, it is possible in this way toincorporate into the copolymers functional groups by means of which thecopolymers may be incorporated by crosslinking into the coatings,adhesive films, and seals produced from the powder slurries and powdercoating materials of the invention.

Monomers (b) used comprise compounds of the general formula I.

In the general formula I, the radicals R¹, R², R³ and R⁴ eachindependently of one another are hydrogen atoms or substituted orunsubstituted alkyl, cycloalkyl, alkylcycloalkyl, cycloalkylalkyl, aryl,alkylaryl, cycloalkylaryl, arylalkyl or arylcycloalkyl radicals, withthe proviso that at least two of the variables R¹, R², R³ and R⁴ aresubstituted or unsubstituted aryl, arylalkyl or arylcycloalkyl radicals,especially substituted or unsubstituted aryl radicals.

Examples of suitable alkyl radicals are methyl, ethyl, propyl,isopropyl, n-butyl, isobutyl, tert-butyl, amyl, hexyl or 2-ethylhexyl.

Examples of suitable cycloalkyl radicals are cyclobutyl, cyclopentyl orcyclohexyl.

Examples of suitable alkylcycloalkyl radicals are methylenecyclohexane,ethylenecyclohexane or propane-1,3-diylcyclohexane.

Examples of suitable cycloalkylalkyl radicals are 2-, 3- or 4-methyl-,-ethyl-, -propyl- or -butylcyclohex-1-yl.

Examples of suitable aryl radicals are phenyl, naphthyl or biphenylyl.

Examples of suitable alkylaryl radicals are benzyl or ethylene- orpropane-1,3-diylbenzene.

Examples of suitable cycloalkylaryl radicals are 2-, 3- or4-phenylcyclohex-1-yl.

Examples of suitable arylalkyl radicals are 2-, 3- or 4-methyl-,-ethyl-, -propyl- or -butylphen-1-yl.

Examples of suitable arylcycloalkyl radicals are 2-, 3- or4-cyclohexylphen-1-yl.

The above-described radicals R¹, R², R³ and R⁴ may be substituted. Thesubstituents used may comprise electron-withdrawing or electron-donatingatoms or organic radicals.

Examples of suitable substituents are halogen atoms, especially chlorineand fluorine, nitrile groups, nitro groups, partially or fullyhalogenated, especially chlorinated and/or fluorinated, alkyl,cycloalkyl, alkylcycloalkyl, cycloalkylalkyl, aryl, alkylaryl,cycloalkylaryl, arylalkyl and arylcycloalkyl radicals, including thoseexemplified above, especially tert-butyl; aryloxy, alkyloxy andcycloalkyloxy radicals, especially phenoxy, naphthoxy, methoxy, ethoxy,propoxy, butyloxy or cyclohexyloxy; arylthio, alkylthio andcycloalkylthio radicals, especially phenylthio, naphthylthio,methylthio, ethylthio, propylthio, butylthio or cyclohexylthio; hydroxylgroups; and/or primary, secondary and/or tertiary amino groups,especially amino, N-methylamino, N-ethylamino, N-propylamino,N-phenylamino, N-cyclohexylamino, N,N-dimethylamino, N,N-diethylamino,N,N-dipropylamino, N,N-diphenylamino, N,N,-dicyclohexylamino,N-cyclohexyl-N-methylamino and N-ethyl-N-methylamino.

Examples of monomers (b) whose use is particularly preferred inaccordance with the invention are diphenylethylene,dinaphthaleneethylene, cis- or trans-stilbene,vinylidenebis(4-N,N-dimethylaminobenzene),vinylidenebis(4-aminobenzene), and vinylidenebis(4-nitrobenzene).

In accordance with the invention, the monomers (b) may be usedindividually or as a mixture of at least two monomers (b).

In terms of the reaction regime and the properties of the resultantcopolymers, especially the acrylate copolymers, diphenylethylene is ofvery particular advantage and is therefore used with very particularpreference in accordance with the invention.

The monomers (a) and (b) to be used in accordance with the invention arereacted with one another in the presence of at least one free-radicalinitiator to form the copolymer. Examples of initiators which can beused are: dialkyl peroxides, such as di-tert-butyl peroxide or dicumylperoxide; hydroperoxides, such as cumene hydroperoxide or tert-butylhydroperoxide; peresters, such as tert-butyl perbenzoate, tert-butylperpivalate, tert-butyl per-3,5,5-trimethylhexanoate or tert-butylper-2-ethylhexancate; potassium, sodium or ammonium peroxodisulfate;azodinitriles such as azobisisobutyronitrile; C—C-cleaving initiatorssuch as benzpinacol silyl ethers; or a combination of a nonoxidizinginitiator with hydrogen peroxide.

It is preferred to add comparatively large amounts of free-radicalinitiator, the proportion of the initiator in the reaction mixturebeing, based in each case on the overall amount of the monomers (a) andof the initiator, with particular preference from 0.5 to 50% by weight,with very particular preference from 1 to 20% by weight, and inparticular from 2 to 15% by weight.

Preferably, the weight ratio of initiator to the monomers (b) is from4:1 to 1:4, with particular preference from 3:1 to 1:3, and inparticular from 2:1 to 1:2. Further advantages result if the initiatoris used in excess within the stated limits.

The free-radical copolymerization is preferably conducted in theapparatus mentioned above, especially stirred tanks or Taylor reactors,the Taylor reactors being designed such that the conditions of Taylorflow are met over the entire reactor length, even if the kinematicviscosity of the reaction medium alters greatly, and in particularincreases, owing to the copolymerization.

The copolymerization is conducted in an aqueous medium. An example of asuitable aqueous medium is the above-described aqueous medium forinventive use, which may include additives and/or organic solventsand/or other dissolved solid, liquid or gaseous organic and/or inorganicsubstances of low and/or high molecular mass, provided these do notadversely affect, or even inhibit, the copolymerization. The aqueousmedium used for the copolymerization is preferably pigment-free.

The copolymerization is preferably conducted in the presence of at leastone base. Particular preference is given to low molecular mass basessuch as sodium hydroxide solution, potassium hydroxide solution,ammonia, diethanolamine, triethanolamine, mono-, di- and triethylamine,and/or dimethylethanolamine, especially ammonia and/or di- and/ortriethanolamine.

The copolymerization is advantageously conducted at temperatures aboveroom temperature and below the lowest decomposition temperature of themonomers used in each case, preference being given to a chosentemperature range of from 10 to 150° C., with very particular preferencefrom 70 to 120° C., and in particular from 80 to 110° C.

When using particularly volatile monomers (a) and/or (b), thecopolymerization may also be conducted under pressure, preferably underfrom 1.5 to 3000 bar, with particular preference from 5 to 1500 bar, andin particular from 10 to 1000 bar.

In terms of the molecular weight distributions, there are norestrictions whatsoever imposed on the copolymer. Advantageously,however, the copolymerization is conducted so as to give a molecularweight distribution Mw/Mn, measured by gel permeation chromatographyusing polystyrene as standard, of ≦4, with particular preference ≦2, andin particular ≦1.5, and in certain cases even ≦1.3. The molecularweights of the constituents (A) may be controlled within wide limits bythe choice of ratio of monomer (a) to monomer (b) to free-radicalinitiator. In this context, the amount of monomer (b) in particulardetermines the molecular weight, specifically such that the higher theproportion of monomer (b), the lower the resultant molecular weight.

The copolymer resulting from the copolymerization is obtained as amixture with the aqueous medium, generally in the form of a dispersion.In this form it can be used as an emulsifier directly or else isolatedas a solid and then passed on for use in accordance with the invention.

The emulsifier may also be introduced, in particular in the form of asolid, into the melts and/or, in particular in the form of a dispersion,into the aqueous media. Preferably it is introduced in the form of adispersion into the aqueous media for inventive use.

The amount of the emulsifiers that is used in the process of theinvention may vary greatly and is guided by the requirements of eachindividual case. For instance, they may be used in the customary amountsknown from the prior art for emulsifiers. They are preferably used in anamount of from 0.01 to 5.0, more preferably from 0.02 to 4.5, withparticular preference from 0.03 to 4, with very particular preferencefrom 0.04 to 3.5, and in particular from 0.05 to 3% by weight, based ineach case on the solids of the emulsion (precursor of the powder slurryof the invention) or of the powder slurry of the invention.

When the above-described, particularly preferred emulsifiers are used,the aqueous medium for use in accordance with the invention may have aparticularly high nanoparticle content, which is a further valuableadvantage of the process of the invention.

The preparation of the aqueous medium for use in accordance with theinvention has no special features in terms of its method but insteadtakes place by suspending at least one pigment in water using thecustomary and known techniques and apparatus. In this context it ispreferred to prepare presuspensions of pigments in mixtures of water andemulsifiers and/or wetting agents, which are then ground to the requiredparticle sizes in suitable apparatus, such as stirred mills.

When the liquid is emulsified in the aqueous medium for use inaccordance with the invention, the ratio of liquid to aqueous medium ischosen so as to give the desired pigment content in the powder slurry ofthe invention. Said content is preferably from 1 to 90, more preferablyfrom 2 to 85, with particular preference from 3 to 80, with veryparticular preference from 4 to 75, and in particular 75% by weight,based in each case on the solids of the powder slurry of the invention.

When the liquid is emulsified in the aqueous medium for use inaccordance with the invention, the pigments may be partitioneddifferently between the disperse phase, i.e., the melted and later solidparticles, and the continuous phase, i.e., the aqueous medium.

In one embodiment of the process of the invention, the emulsified orsuspended particles comprise at least one pigment; i.e., the totalamount of the pigments used is present in and/or on the particles.

In another embodiment of the process of the invention, the emulsified orsuspended particles contain no pigment; i.e., all of the pigments arepresent in the form of a separate solid phase. Regarding their particlesize, the comments made above apply analogously.

In yet another embodiment of the process of the invention, theemulsified or suspended particles comprise, in the sense set out above,a portion of the pigments used, while the other portion of the pigmentsis present in the form of a separate solid phase. In this case, thefraction present in the particles may comprise the majority, i.e., morethan 50%, of the pigments used. It is, however, also possible for lessthan 50% to be present in and/or on the particles. Regarding theparticle sizes, the comments made above apply analogously here as well.

Which variant of the process of the invention is given preference inpreparing the pigmented powder coating materials of the inventiondepends in particular on the nature of the pigments and their functions.Particular preference is given to employing the variant in which all, orthe predominant fraction, of the pigments are/is present in and/or onthe emulsified and suspended particles.

Dispersing units which can be used are all customary and knowndispersing units suitable for emulsifying melts in aqueous media.

Examples of suitable dispersing units are inline dissolvers having arotor/stator construction, preferably toothed-ring dispersing unitsparticularly having at least one cylindrical arrangement of at least twocomminutor rings (stator and rotor) which are seated on holders, are inmutual embrace, and are rotatable in opposite directions relative to oneanother, the working gap produced by the relative movement betweenstator and rotor having walls which extend nonparallelwise with respectto one another. In this case it is of advantage if the rotor rotates inthe sense of an opening working gap. Examples of highly suitabletoothed-ring dispersing units are described in detail in the patent EP 0648 537 A1. They are sold under the trade name K-Generatoren byKinematica AG, Lucerne, Switzerland.

The ratio of disperse phase to continuous phase may vary widely and isguided by the requirements of the specific case. Preferably, the volumeratio of liquid to aqueous medium is chosen so as to give an emulsionand a suspension with a solids content of at least 40% by weight, morepreferably at least 45% by weight, with particular preference at least50% by weight, with very particular preference at least 55% by weight,and in particular at least 60% by weight.

The residence times of the liquid and of the aqueous phase for inventiveuse in the dispersing unit is preferably from 0.5 to 20, more preferablyfrom 1 to 18, with particular preference from 1.5 to 16, with veryparticular preference from 1.5 to 15, and in particular from 1.5 to 10seconds.

Following emulsification, the resultant emulsified liquid particles arecooled, thereby giving suspended, dimensionally stable particles of thepowder slurries of the invention. Preferably, the emulsion is cooledimmediately following its preparation without further aftertreatment. Inthis context it is preferred to employ the methods described in DE 19652 813 A1, column 8 lines 9 to 17.

When preparing powder slurries of the invention which can be crosslinkedwith actinic radiation it is advantageous to work in the absence ofactinic radiation.

The emulsified liquid particles and the suspended dimensionally stableparticles comprise or consist of at least one binder. Accordingly, thebinders are used as starting products in the process of the invention.

The binder per se may be curable physically, thermally, with actinicradiation, and both thermally and with actinic radiation. In general itis present in the particles in an amount of from 5.0 to 100, preferablyfrom 6.0 to 95, more preferably from 7.0 to 90, with particularpreference from 8.0 to 85, with very particular preference from 9.0 to80, and in particular from 10 to 80% by weight, based in each case onthe total amount of the particles.

The binder preferably has a glass transition temperature above roomtemperature, more preferably from 30 to 80, with particular preferencefrom 40 to 70, with very particular preference from 40 to 60, and inparticular about 50° C. (measured by means of Differential ScanningCalorimetry (DSC)).

The molecular weight of the binder may vary very widely. In accordancewith the invention it is preferred not to choose too high a bindermolecular weight, since otherwise problems may occur in the course ofits filming. Preferably, the molecular weight is from 500 to 30,000,more preferably from 500 to 25,000, with particular preference from 500to 20,000, with very particular preference from 500 to 15,000, and inparticular from 500 to 10,000.

The binders are oligomeric and polymeric resins. Oligomers are resinscontaining at least 2 to 15 monomer units in their molecule. In thecontext of the present invention, polymers are resins containing atleast 10 repeating monomer units in their molecule. For further detailsof these terms, refer to Römpp Lexikon Lacke und Druckfarben, GeorgThieme Verlag, Stuttgart, N.Y., 1998, “oligomers”, page 425.

It is of advantage if the minimum film formation temperature of thebinders is in the region of their glass transition temperature Tg and inparticular at at least 25° C. The minimum film formation temperature maybe determined by drawing the aqueous dispersion of the binder down ontoa glass plate using a coating bar and heating the drawdown in a gradientoven. The temperature at which the pulverulent layer forms a film isreferred to—as the minimum film—formation temperature. For furtherdetails, refer to Römpp Lexikon Lacke und Druckfarben, Georg ThiemeVerlag, Stuttgart., N.Y., 1998, “minimum film formation temperature”,page 391.

Examples of suitable binders are random, alternating and/or block,linear and/or branched and/or comb addition (co)polymers of olefinicallyunsaturated monomers, or polyaddition resins and/or polycondensationresins. For further details of these terms, refer to Römpp Lexikon Lackeund Druckfarben, Georg Thieme Verlag, Stuttgart, N.Y., 1998, page 457,“polyaddition” and “polyaddition resins (polyadducts)”, and pages 463and 464, “polycondensates”, “polycondensation” and “polycondensationresins”, and also pages 73 and 74, “binders”.

Examples of suitable addition (co)polymers are (meth)acrylate(co)polymers or partially saponified polyvinyl esters, especially(meth)acrylate copolymers.

Examples of suitable polyaddition resins and/or polycondensation resinsare polyesters, alkyds, polyurethanes, polylactones, polycarbonates,polyethers, epoxy resin-amine adducts, polyureas, polyamides,polyimides, polyester-polyurethanes, polyetherpolyurethanes orpolyester-polyether-polyurethanes, especially polyester-polyurethanes.

Of these binders, the (meth)acrylate (co)polymers have particularadvantages and are therefore used with particular preference.

The self-crosslinking binders of the thermally curable powder slurriesof the invention contain reactive functional groups which are able toenter into crosslinking reactions with groups of their own kind or withcomplementary reactive functional groups.

The externally crosslinking binders contain reactive functional groupswhich are able to enter into crosslinking reactions with complementaryreactive functional groups that are present in crosslinking agents.

Examples of suitable complementary reactive functional groups for use inaccordance with the invention are summarized in the following overview.In the overview, the variable R stands for an acylic or cyclic aliphaticradical, an aromatic radical and/or an aromatic-aliphatic (araliphatic)radical; the variables R′ and R″ stand for identical or differentaliphatic radicals or are linked with one another to form an aliphaticor heteroaliphatic ring.

Overview: Examples of complementary functional groups Binder andCrosslinking agent and crosslinking agent or binder —SH —C(O)—OH —NH₂—C(O)—O—C(O)— —OH —NCO —O—(CO)—NH—(CO)—NH₂ —NH—C(O)—OR —O—(CO)—NH₂—CH₂—OH >NH —CH₂—O—R —NH—CH₂—O—R —NH—CH₂—OH —N(—CH₂—O—R)₂—NH—C(O)—CH(—C(O)OR)₂ —NH—C(O)—CH(—C(O)OR)(—C(O)—R) —NH—C(O)—NR′R″>Si(OR)₂

—C(O)—OH

—C(O)—N(CH₂—CH₂—OH)₂

The selection of the respective complementary groups is guided on theone hand by the consideration that, during the preparation, storage,application, and melting of the powder slurries of the invention, theyshould not enter into any unwanted reactions, particularly no prematurecrosslinking, and/or, where appropriate, must not disrupt or inhibitcuring with actinic radiation, and on the other by the temperature rangewithin which crosslinking is to take place.

In the case of the powder slurries of the invention it is preferred toemploy crosslinking temperatures from 60 to 180° C. It is thereforepreferred to employ binders containing thio, hydroxyl, N-methylolamino,N-alkoxymethylamino, imino, carbamate, allophanate and/or carboxylgroups, preferably hydroxyl or carboxyl groups, on the one hand andpreferred to employ crosslinking agents containing anhydride, carboxyl,epoxy, blocked isocyanate, urethane, methylol, methylol ether, siloxane,carbonate, amino, hydroxyl and/or beta-hydroxyalkyl amide groups,preferably epoxy, beta-hydroxyalkylamide, blocked isocyanate, urethaneor alkoxymethylamino groups, on the other.

In the case of self-crosslinking powder slurries of the invention, thebinders include in particular methylol, methylol ether and/orN-alkoxymethylamino groups.

Complementary reactive functional groups particularly suitable for usein the powder slurries and powder coating materials of the invention are

-   -   carboxyl groups on the one hand and epoxide groups and/or        beta-hydroxyalkylamide groups on the other, and    -   hydroxyl groups on the one hand and blocked isocyanate, urethane        or alkoxymethylamino groups on the other.

The functionality of the binders in respect of the reactive functionalgroups described above may vary very widely and depends in particular onthe desired crosslinking density and/or on the functionality of thecrosslinking agents employed in each case. In the case ofcarboxyl-containing binders, for example, the acid number is preferablyfrom 10 to 100, more preferably from 15 to 80, with particularpreference from 20 to 75, with very particular preference from 25 to 70,and, in particular, from 30 to 65 mg KOH/g. Alternatively, in the caseof hydroxyl-containing binders, the OH number is preferably from 15 to300, more preferably from 20 to 250, with particular preference from 25to 200, with very particular preference from 30 to 150, and, inparticular, from 35 to 120 mg KOH/g. Alternatively, in the case ofbinders containing epoxide groups, the epoxide equivalent weight ispreferably from 400 to 2500, more preferably from 420 to 2200, withparticular preference from 430 to 2100, with very particular preferencefrom 440 to 2000, and, in particular, from 440 to 1900.

The complementary functional groups described above can be incorporatedinto the binders in accordance with the customary and known methods ofpolymer chemistry. This can be done, for example, by incorporatingmonomers which carry the corresponding reactive functional groups,and/or with the aid of polymer-analogous reactions.

Examples of suitable olefinically unsaturated monomers containingreactive functional groups are the monomers (a) described below,especially

-   (i) monomers which carry at least one hydroxyl, amino,    alkoxymethylamino, carbamate, allophanate or imino group per    molecule, such as    -   hydroxyalkyl esters of acrylic acid, methacrylic acid or another        alpha,beta-olefinically unsaturated carboxylic acid, which are        derived from an alkylene glycol which is esterified with the        acid, or which are obtainable by reacting the        alpha,beta-olefinically unsaturated carboxylic acid with an        alkylene oxide such as ethylene oxide or propylene oxide,        especially hydroxyalkyl esters of acrylic acid, methacrylic        acid, ethacrylic acid, crotonic acid, maleic acid, fumaric acid        or itaconic acid, in which the hydroxyalkyl group contains up to        20 carbon atoms, such as 2-hydroxyethyl, 2-hydroxypropyl,        3-hydroxypropyl, 3-hydroxybutyl, 4-hydroxybutyl acrylate,        methacrylate, ethacrylate, crotonate, maleate, fumarate or        itaconate; or hydroxycycloalkyl esters such as        1,4-bis(hydroxymethyl)cyclohexane,        octahydro-4,7-methano-1H-indenedimethanol or methylpropanediol        monoacrylate, monomethacrylate, monoethacrylate, monocrotonate,        monomaleate, monofumarate or monoitaconate; reaction products of        cyclic esters, such as epsilon-caprolactone and these        hydroxyalkyl or hydroxycycloalkyl esters;    -   olefinically unsaturated alcohols such as allyl alcohol;    -   polyols such as trimethylolpropane monoallyl or diallyl ether or        pentaerythritol monoallyl, diallyl or triallyl ether;    -   reaction products of acrylic acid and/or methacrylic acid with        the glycidyl ester of an alpha-branched monocarboxylic acid        having 5 to 18 carbon atoms per molecule, especially a Versatic®        acid, or instead of the reaction product an equivalent amount of        acrylic and/or methacrylic acid, which is then reacted during or        after the polymerization reaction with the glycidyl ester of an        alpha-branched monocarboxylic acid having 5 to 18 carbon atoms        per molecule, especially a Versatic® acid;    -   aminoethyl acrylate, aminoethyl methacrylate, allylamine or        N-methyliminoethyl acrylate;    -   N,N-di(methoxymethyl)aminoethyl acrylate or methacrylate or        N,N-di(butoxymethyl)aminopropyl acrylate or methacrylate;    -   (meth)acrylamides such as (meth)acrylamide, N-methyl-,        N-methylol-, N,N-dimethylol-, N-methoxymethyl-,        N,N-di(methoxymethyl)-, N-ethoxymethyl- and/or        N,N-di(ethoxyethyl)-(meth)acrylamide;    -   acryloyloxy- or methacryloyloxyethyl, -propyl or -butyl        carbamate or allophahate; further examples of suitable monomers        containing carbamate groups are described in the patents U.S.        Pat. No. 3,479,328, U.S. Pat. No. 3,674,838, U.S. Pat. No.        4,126,747, U.S. Pat. No. 4,279,833 and U.S. Pat. No. 4,340,497;-   (ii) monomers (a3) which carry at least one acid group per molecule,    such as    -   acrylic acid, beta-carboxyethyl acrylate, methacrylic acid,        ethacrylic acid, crotonic acid, maleic acid, fumaric acid or        itaconic acid;    -   olefinically unsaturated sulfonic or phosphonic acids or their        partial esters;    -   mono(meth)acryloyloxyethyl maleate, succinate or phthalate; or    -   vinylbenzoic acid (all isomers), alpha-methylvinylbenzoic acid        (all isomers) or vinylbenzenesulfonic acid (all isomers);-   (iii) monomers containing epoxide groups, such as the glycidyl ester    of acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid,    maleic acid, fumaric acid or itaconic acid, or allyl glycidyl ether.

They are preferably used to prepare the inventively preferred(meth)acrylate copolymers, especially the ones containing glycidylgroups.

More highly functional monomers of the type described above aregenerally used in minor amounts. For the purposes of the presentinvention, minor amounts of higher-functional monomers are those amountswhich do not lead to crosslinking or gelling of the addition copolymers,in particular of the (meth)acrylate copolymers, unless the specificdesire is to prepare crosslinked polymeric microparticles.

Examples of suitable monomer units for introducing reactive functionalgroups into polyesters or polyester-polyurethanes are2,2-dimethylolethyl- or -propylamine blocked with a ketone, theresulting ketoxime group being hydrolyzed again following incorporation;or compounds containing two hydroxyl groups or two primary and/orsecondary amino groups and also at least one acid group, in particularat least one carboxyl group and/or at least one sulfonic acid group,such as dihydroxypropionic acid, dihydroxysuccinic acid,dihydroxybenzoic acid, 2,2-dimethylolacetic acid,2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid,2,2-dimethylolpentanoic acid, 2,2-diaminovaleric acid,3,4-diaminobenzoic acid, 2,4-diaminotoluenesulfonic acid or2,4-diaminodiphenyl ether sulfonic acid.

One example of introducing reactive functional groups by way ofpolymer-analogous reactions is the reaction of hydroxyl-containingresins with phosgene, resulting in resins containing chloroformategroups, and the polymer-analogous reaction of thechloroformate-functional resins with ammonia and/or primary and/orsecondary amines to give resins containing carbamate groups. Furtherexamples of suitable methods of this kind are known from the patentsU.S. Pat. No. 4,758,632 A1, U.S. Pat. No. 4,301,257 A1 and U.S. Pat. No.2,979,514 A1. Moreover, it is possible to introduce carboxyl groups bypolymer-analogous reaction of hydroxyl groups with carboxylicanhydrides, such as maleic anhydride or phthalic anhydride.

The binders of the dual-cure powder slurries and powder coatingmaterials of the invention further comprise on average per molecule atleast one, preferably at least two, group(s) having at least one bondthat can be activated with actinic radiation.

For the purposes of the present invention, a bond that can be activatedwith actinic radiation is a bond which on exposure to actinic radiationbecomes reactive and, with other activated bonds of its kind, entersinto addition polymerization reactions and/or crosslinking reactionswhich proceed in accordance with free-radical and/or ionic mechanisms.Examples of suitable bonds are carbon-hydrogen single bonds orcarbon-carbon, carbon-oxygen, carbon-nitrogen, carbon-phosphorus orcarbon-silicon single bonds or double bonds. Of these, the carbon-carbondouble bonds are particularly advantageous and are therefore used withvery particular preference in accordance with the invention. For thesake of brevity, they are referred to below as double bonds.

Accordingly, the group which is preferred in accordance with theinvention comprises one double bond or two, three or four double bonds.If more than one double bond is used, the double bonds can beconjugated. In accordance with the invention, however, it is ofadvantage if the double bonds are present in isolation, in particulareach being present terminally, in the group in question. It is ofparticular advantage in accordance with the invention to use two doublebonds or, in particular, one double bond.

The dual-cure binder contains on average at least one of theabove-described groups that can be activated with actinic radiation.This means that the functionality of the binder in this respect isintegral, i.e., for example, is two, three, four, five or more, ornonintegral, i.e., for example, is from 2.1 to 10.5 or more. Thefunctionality chosen depends on the requirements imposed on therespective pigmented dual-cure powder slurries and powder coatingmaterials of the invention.

If more than one group that can be activated with actinic radiation isused on average per molecule, the groups are structurally different fromone another or of the same structure.

If they are structurally different from one another, this means, in thecontext of the present invention, that use is made of two, three, fouror more, but especially two, groups that can be activated by actinicradiation, these groups deriving from two, three, four or more, butespecially two, monomer classes.

Examples of suitable groups are (meth)acrylate, ethacrylate, crotonate,cinnamate, vinyl ether, vinyl ester, dicyclopentadienyl, norbornenyl,isoprenyl, isopropenyl, allyl or butenyl groups; dicyclopentadienyl,norbornenyl, isoprenyl, isopropenyl, allyl or butenyl ether groups; ordicyclopentadienyl, norbornenyl, isoprenyl, isopropenyl, allyl orbutenyl ester groups, but especially acrylate groups.

Preferably, the groups are attached to the respective parent structuresof the binders via urethane, urea, allophanate, ester, ether and/oramide groups, but in particular via ester groups. Normally, this occursas a result of customary and known polymer-analogous reactions such as,for instance, the reaction of pendant glycidyl groups with theolefinically unsaturated monomers described above that contain an acidgroup, of pendant hydroxyl groups with the halides of these monomers, ofhydroxyl groups with isocyanates containing double bonds such as vinylisocyanate, methacryloyl isocyanate and/or1-(1-isocyanato-1-methylethyl)-3-(1-methylethenyl)benzene (TMI® from thecompany CYTEC), or of isocyanate groups with the above-describedhydroxyl-containing monomers.

Alternatively, in the particles it is possible to employ mixtures ofpurely thermally curable binders and binders that are curable purelywith actinic radiation.

The material composition of the binders does not basically have anyspecial features; rather, suitable binders include

-   -   all the binders envisaged for use in powder clearcoat slurries        curable thermally and/or with actinic radiation that are        described in the U.S. Pat. No. 4,268,542 A1 or U.S. Pat. No.        5,379,947 A1 and in the patent applications DE 27 10 421 A1, DE        195 40 977 A1, DE 195 18 392 A1, DE 196 17 086 A1, DE 196 18 657        A1, DE 196 52 813 A1, DE 196 17 086 A1, DE 198 14 471 A1, DE 196        13 547 A1, DE 198 41 842 A1 or DE 198 41 408 A1, in the German        patent applications DE 199 08 018.6 or DE 199 08 013.5,        unpublished at the priority date of the present specification,        or in the European patent EP 0 652 264 A1;    -   all the binders envisaged for use in dual-cure clearcoats that        are described in the patent applications DE 198 35 296 A1, DE        197 36 083 A1 or DE 198 41 842 A1; or    -   all the binders envisaged for use in thermally curable powder        clearcoats and described in the German patent application DE 42        22 194 A1, in the product information bulletin from BASF        Lacke+Farben AG, “Pulverlacke”, 1990, or in the BASF Coatings AG        brochure “Pulverlacke, Pulverlacke für industrielle        Anwendungen”, January 2000.

Suitable additional binders for the dual-cure powder slurries and powdercoating materials, are the binders envisaged for use in UV-curableclearcoats and powder clearcoats and described in European patentapplications EP 0 928 800 A1, EP 0 636 669 A1, EP 0 410 242 A1, EP 0 783534 A1, EP 0 650 978 A1, EP 0 650 979 A1, EP 0 650 985 A1, EP 0 540 884A1, EP 0 568 967 A1, EP 0 054 505 A1 or EP 0 002 866 A1, in the Germanpatent applications DE 197 09 467 A1, DE 42 03 278 A1, DE 33 16 593 A1,DE 38 36 370 A1, DE 24 36 186 A1 or DE 20 03 579 B1, in theinternational patent applications WO 97/46549 or WO 99/14254, or in theAmerican patents U.S. Pat. No. 5,824,373 A1, U.S. Pat. No. 4,675,234 A1,U.S. Pat. No. 4,634,602 A1, U.S. Pat. No. 4,424,252 A1, U.S. Pat. No.4,208,313 A1, U.S. Pat. No. 4,163,810 A1, U.S. Pat. No. 4,129,488 A1,U.S. Pat. No. 4,064,161 A1 or U.S. Pat. No. 3,974,303 A1.

The preparation of the binders also has no special features in terms ofits method but instead takes place with the aid of the customary andknown methods of polymer chemistry, as described in detail, for example,in the patent documents cited above.

Further examples of suitable preparation processes for (meth)acrylatecopolymers are described in the European patent application EP 0 767 185A1, in the German patents DE 22 14 650 B1 or DE 27 49 576 B1, and in theAmerican patents U.S. Pat. No. 4,091,048 A1, U.S. Pat. No. 3,781,379 A1,U.S. Pat. No. 5,480,493 A1, U.S. Pat. No. 5,475,073 A1 or U.S. Pat. No.5,534,598 A1, or in the standard work Houben-Weyl, Methoden derorganischen Chemie, 4th edition, volume 14/1, pages 24 to 255, 1961.Suitable reactors for the copolymerization include the customary andknown stirred tanks, stirred tank cascades, tube reactors, loop reactorsor Taylor reactors, as described for example in the patents and patentapplications DE 1 071 241 B1, EP 0 498 583 A1, and DE 198 28 742 A1 orin the article by K. Kataoka in Chemical Engineering Science, volume 50,No. 9, 1995, pages 1409 to 1416.

The preparation of suitable polyesters and alkyd resins are alsodescribed, for example, in the standard work Ullmanns Encyklopädie dertechnischen Chemie, 3rd edition, Volume 14, Urban & Schwarzenberg,Munich, Berlin, 1963, pages 80 to 89 and pages 99 to 105, and also inthe following books: “Resines Alkydes-Polyesters” by J. Bourry, Dunod,Paris, 1952, “Alkyd Resins” by C. R. Martens, Reinhold PublishingCorporation, New York, 1961, and also “Alkyd Resin Technology” by T. C.Patton, Interscience Publishers, 1962.

The preparation of suitable polyurethanes and/or acrylated polyurethanesis described, for example, in the patent applications EP 0 708 788 A1,DE 44 01 544 A1, and DE 195 34 361 A1.

Of these binders, the (meth)acrylate copolymers containing epoxidegroups, having an epoxide equivalent weight of preferably from 400 to2500, more preferably from 420 to 2200, with particular preference from430 to 2100, with very particular preference from 440 to 2000, and, inparticular, from 440 to 1900, a number-average molecular weight(determined by gel permeation chromatography using a polystyrenestandard) of preferably from 2000 to 20,000 and in particular from 3000to 10,000, and a glass transition temperature (T_(g)) of preferably from30 to 80, more preferably from 40 to 70 and in particular from 40 to 60°C. (measured by means of differential scanning calorimetry (DSC)), assuitable in particular for use in thermally curable powder clearcoatslurries (see above) and as described, furthermore, in the patents andpatent applications EP 0 299 420 A1, DE 22 14 650 B1, DE 27 49 576 B1,U.S. Pat. No. 4,091,048 A1 and U.S. Pat. No. 3,781,379 A1, areparticularly advantageous and are used with particular preference.

The externally crosslinking powder slurries of the invention curablethermally or both thermally and with actinic radiation, and/or theparticles used for their preparation, include at least one crosslinkingagent containing the reactive functional groups complementary to thereactive functional groups of the binders. The skilled worker willtherefore easily be able to select the crosslinking agents suitable forthe case in hand.

In the process of the invention, the crosslinking agents are suppliedpreferably in the form of separate melts to the static mixer. The ratioof binder melt to crosslinking agent melt is guided by the desired ratioof complementary reactive functional groups in the powder slurries ofthe invention.

Examples of suitable crosslinking agents are

-   -   amino resins, as described for example in Römpp Lexikon Lacke        und Druckfarben, Georg Thieme Verlag, 1998, page 29, “amino        resins”, in the textbook “Lackadditive” [Additives for coatings]        by Johan Bieleman, Wiley-VCH, Weinheim, N.Y., 1998, pages 242        ff., in the book “Paints, Coatings and Solvents”, second,        completely revised edition, edited by D. Stoye and W. Freitag,        Wiley-VCH, Weinheim, N.Y., 1998, pages 80 ff., in the patents        U.S. Pat. No. 4,710,542 A, and EP 0 245 700 A1, and in the        article by B. Singh and coworkers, “Carbamylmetbylated        Melamines, Novel Crosslinkers for the Coatings Industry”, in        Advanced Organic Coatings Science and Technology Series, 1991,        Volume 13, pages 193 to 207;    -   carboxyl-containing compounds or resins, as described for        example in the patent DE 196 52 813 A1 or 198 41 408 A1,        especially 1,12-dodecanedioic acid (1,10-decanedicarboxylic        acid);    -   resins or compounds containing epoxy groups, as described for        example in the patents EP 0 299 420 A1, DE 22 14 650 B1, DE 27        49 576 B1, U.S. Pat. No. 4,091,048 A1, and U.S. Pat. No.        3,781,379 A1;    -   blocked polyisocyanates, as described for example in the patents        U.S. Pat. No. 4,444,954 A1, DE 196 17 086 A1, DE 196 31 269 A1,        EP 0 004 571 A1, and EP 0 582 051 A1;    -   beta-hydroxyalkylamides such as        N,N,N′,N′-tetrakis(2-hydroxyethyl)adipamide or        N,N,N′,N′-tetrakis(2-hydroxypropyl)adipamide; and/or    -   tris(alkoxycarbonylamino)triazines, as described in the patents        U.S. Pat. No. 4,939,213 A1, U.S. Pat. No. 5,084,541 A1, U.S.        Pat. No. 5,288,865 A1 and EP 0 604 922 A1.

The amount of the crosslinking agents in the dimensionally stableparticles may likewise vary very widely and is guided by therequirements of each individual case, in particular by the number ofreactive functional groups present and by the target crosslinkingdensity of the coatings, adhesive films, and seals produced from thepowder slurries of the invention. The amount is preferably from 1 to 50,more preferably from 2 to 45, with particular preference from 3 to 40,with very particular preference from 4 to 35, and in particular from 5to 30% by weight, based on the solids of the powder slurries of theinvention.

In addition to the above-described pigments the powder slurries of theinvention may comprise molecularly dispersed organic dyes as additives.

In the context of the process of the invention, the organic dyes may besupplied to the static mixer in the form of separate melts or in thebinder and/or crosslinking agent melts and/or may be present in theabove-described aqueous media for inventive use. When the liquid isemulsified in the aqueous medium for use in accordance with theinvention, it may be partitioned differently between the disperse phase,i.e., the melted and later solid particles, and the continuous phase,i.e., the aqueous medium.

These molecularly dispersed dyes may be present either in the emulsifiedor suspended particles or in the continuous phase, i.e., the aqueousmedium. Alternatively, they may be present in the particles and in thecontinuous phase. In this case, the fraction that is present in theparticles may comprise the majority, i.e., more than 50%, of the organicdyes used. However, less than 50% may be present, alternatively, in theparticles. The distribution of the organic dyes between the phases maycorrespond to the thermodynamic equilibrium resulting from thesolubility of the organic dyes in the phases. However, the distributionmay also be far removed from the thermodynamic equilibrium.

Suitable organic dyes are all those soluble in the sense outlined abovein the powder slurries of the invention. Lightfast organic dyes arehighly suitable. Lightfast organic dyes having little or no tendency tomigrate from the coatings, adhesive films, and seals produced from thepowder slurries of the invention are especially suitable. The migrationtendency may be estimated by the skilled worker on the basis of his orher general knowledge of the art and/or determined with the aid ofsimple preliminary rangefinding tests, as part of tinting tests, forexample.

The amount of the molecularly dispersed organic dyes in the powderslurries of the invention may vary extremely widely and is guidedprimarily by the color and by the shade that is to be established, andalso by the amount of any pigments present.

Further examples of suitable additives are UV absorbers, antioxidants,light stabilizers, free-radical scavengers, devolatilizers, wettingagents, slip additives, polymerization inhibitors, crosslinkingcatalysts, thermolabile free-radical initiators, photoinitiators,thermally curable reactive diluents, reactive diluents curable withactinic radiation, adhesion promoters, leveling agents, Theological aids(thickeners), film-forming auxiliaries, flame retardants, corrosioninhibitors, free-flow aids, waxes, siccatives, biocides and/or flattingagents.

Examples of suitable thermally curable reactive diluents arepositionally isomeric diethyloctanediols or hydroxyl-containinghyperbranched compounds or dendrimers, as described in the German patentapplications DE 198 09 643 A1, DE 198 40 605 A1 and DE 198 05 421 A1.

Examples of suitable reactive diluents curable with actinic radiationare those described in Römpp Lexikon Lacke und Druckfarben, Georg ThiemeVerlag, Stuttgart, N.Y., 1998, on page 491 under the entry on “reactivediluents”.

Examples of suitable light stabilizers are HALS compounds,benzotriazoles or oxalanilides.

Examples of suitable antioxidants are hydrazines and phosphoruscompounds.

Examples of suitable polymerization inhibitors are organic phosphites or2,6-di-tert-butylphenol derivatives.

Examples of suitable thermolabile free-radical initiators are dialkylperoxides, hydroperoxides peresters, azo dinitriles or C—C-cleavinginitiators.

Examples of suitable photoinitiators are described in Römpp ChemieLexikon, 9th, expanded and revised edition, Georg Thieme Verlag,Stuttgart, Vol. 4, 1991, or in Römpp Lexikon Lacke und Druckfarben,Georg Thieme Verlag, Stuttgart, 1998, pages 444 to 446.

Examples of suitable crosslinking catalysts are bismuth lactate,citrate, ethylhexanoate or dimethylolpropionate, dibutyltin dilaurate,lithium decanoate or zinc octoate, amine-blocked organic sulfonic acids,quaternary ammonium compounds, amines, imidazole and imidazolederivatives such as 2-styrylimidazole, 1-benzyl-2-methylimidazole,2-methylimidazole and 2-butylimidazole, as described in the Belgianpatent no. 756,693, or phosphonium catalysts such asethyltriphenylphosphonium iodide, ethyltriphenylphosphonium chloride,ethyltriphenylphosphonium thiocyanate, ethyltriphenylphosphoniumacetate-acetic acid complex, tetrabutylphosphonium iodide,tetrabutylphosphonium bromide and tetrabutylphosphonium acetate-aceticacid complex, as described, for example, in the U.S. patents U.S. Pat.No. 3,477,990 A or U.S. Pat. No. 3,341,580 A.

Examples of suitable devolatilizers are diazadicycloundecane or benzoin.

Examples of suitable wetting agents are siloxanes, fluorine compounds,carboxylic monoesters, phosphates, polyacrylic acids and theircopolymers, or polyurethanes.

An example of a suitable adhesion promoter is tricyclodecanedimethanol.

Examples of suitable film-forming auxiliaries are cellulose derivatives.

Examples of suitable rheology control additives are those known from thepatents WO 94/22968, EP 0 276 501 A1, EP 0 249 201 A1, and WO 97/12945;crosslinked polymeric microparticles, as disclosed for example in EP 0008 127 A1; inorganic phyllosilicates such as aluminum magnesiumsilicates, sodium magnesium phyllosilicates and sodium magnesiumfluorine lithium phyllosilicates of the montmorillonite type; silicassuch as Aerosils; or synthetic polymers containing ionic and/orassociative groups such as polyvinyl alcohol, poly(meth)acrylamide,poly(meth)acrylic acid, polyvinylpyrrolidone, styrene-maleic anhydrideor ethylene-maleic anhydride copolymers and their derivatives, orhydrophobically modified ethoxylated urethanes, as described for examplein the patent DE 196 52 813 A1, column 5 lines 28 to 59, orpolyacrylates.

An example of a suitable flatting agent is magnesium stearate.

Further examples of the additives listed above and also of suitableleveling agents, flame retardants, siccatives, dryers, antiskinningagents, corrosion inhibitors, biocides, and waxes are described indetail in the textbook “Lackadditive” [Additives for coatings] by JohanBieleman, Wiley-VCH, Weinheim, N.Y., 1998.

Further suitable additives include low-boiling and high-boiling (“long”)organic solvents, as are commonly used in the field of coatingmaterials. In view of the fact that the powder slurries and powdercoating materials of the invention are preferably free of VOCs, theorganic solvents are used only in exceptional cases.

The powder slurries of the invention have outstanding stability andstorability and their behavior is outstanding. They are outstandinglysuitable as coating materials, adhesives, and sealing compounds, or forpreparing such compositions.

The coating materials of the invention are outstandingly suitable forproducing single-coat or multicoat, color and/or effect, electricallyconductive, magnetically shielding or fluorescent coatings, such asprimer-surfacer coats, basecoats, solid-color topcoats or combinationeffect coats, or single-coat or multicoat clearcoat systems.

The adhesives of the invention are outstandingly suitable for producingadhesive films, and the sealing compounds of the invention areoutstandingly suitable for producing seals.

Very particularly advantages result when the powder slurries of theinvention are used to produce single-coat or multicoat color and/oreffect coating systems or combination effect coats. A combination effectcoat is a coating which performs at least two functions in a colorand/or effect system. Functions of this kind include in particularprotection against corrosion, adhesion promotion, the absorption ofmechanical energy, and the imparting of color and/or effect. Preferably,the combination effect coat serves to absorb mechanical energy and toimpart color and/or effect at the same time; it therefore fulfills thefunctions of a primer-surfacer coat or antistonechip primer and of abasecoat. Preferably, the combination effect coat additionally has acorrosion protection effect and/or adhesion promotion effect.

The pigmented coatings or coating systems may likewise be produced usingwet-on-wet techniques. For example, the pigmented powder slurries of theinvention may be applied to electrocoat films which have not been cured,or not been cured fully, and then the films one above the other arecured together.

In terms of its method, the application of the powder slurries of theinvention has no special features but may take place by any customaryapplication method, such as spraying, knife coating, brushing, flowcoating, dipping, trickling or rolling, for example. It is preferred toemploy spray application methods, such as compressed air spraying,airless spraying, high-speed rotation, electrostatic spray application(ESTA), alone or in conjunction with hot spray applications such as hotair spraying, for example. Here it is advisable to work in the absenceof actinic radiation in order to prevent premature crosslinking of thedual-cure coating materials, adhesives, and sealing compounds of theinvention.

Suitable substrates are all those whose surface is not damaged by theapplication of heat and/or actinic radiation in the course of the curingof the films present thereon. Preferably, the substrates comprisemetals, plastics, wood, ceramic, stone, textile, fiber composites,leather, glass, glass fibers, glass wool and rockwool, mineral- andresin-bound building materials, such as plasterboard and cement slabs orroof tiles, and also composites of these materials.

Accordingly, the coating materials, adhesives, and sealing compounds ofthe invention are outstandingly suitable for coating, bonding, andsealing motor vehicle bodies, parts of motor vehicle bodies, theinterior and exterior of motor vehicles, the inside and outside ofbuildings, doors, windows, furniture, and for coating, bonding andsealing in the context of the industrial coating, for example, of smallparts, such as nuts, bolts, wheel rims or hubcaps, coils, containers,packaging, electrical components, such as motor windings or transformerwindings, and of white goods, such as domestic appliances, boilers, andradiators.

In the case of electrically conductive substrates it is possible to useprimers produced conventionally from the electrodeposition coatingmaterials. Both anodic and cathodic electrocoat materials are suitablefor this purpose, but especially cathodic electrocoat materials.Unfunctionalized and/or nonpolar plastics surfaces may be subjectedprior to coating in a known manner to a pretreatment, such as with aplasma or by flaming, or may be provided with a water-based primer.

The curing of the applied powder slurries of the invention also has nospecial features in terms of its method but it then takes place inaccordance with the customary and known thermal methods, such as heatingin a forced air oven or irradiation using IR lamps. For actinicradiation curing, suitable radiation sources include those such as high-or low-pressure mercury vapor lamps, which may be doped with lead inorder to open up a radiation window up to 405 nm, or electron beamsources. Examples of suitable techniques and apparatus for curing withactinic radiation are described in the German patent application DE 19818 735 A1, column 10 lines 31 to 61.

The resultant coatings of the invention, especially the single-coat ormulticoat color and effect coating systems and combination effect coatsof the invention are easy to produce and have outstanding opticalproperties and very high light, chemical, water, condensation, andweathering resistance. In particular they are free from turbidities andinhomogeneities. They are hard, flexible, and scratch resistant. Theyhave very good reflow properties and outstanding intercoat adhesion, andexhibit good to very good adhesion to customary and known automotiverefinishes.

The adhesive films of the invention bond a very wide variety ofsubstrates to one another firmly and durably and possess high chemicaland mechanical stability even in the case of extreme temperatures and/ortemperature fluctuations.

Similarly, the seals of the invention seal the substrates durably andpossess high chemical and mechanical stability even in the case ofextreme temperatures and/or temperature fluctuations and even inconjunction with exposure to aggressive chemicals.

A further advantage of the dual-cure coating materials, adhesives, andsealing compounds is that, even in the shadow zones of three-dimensionalsubstrates of complex shape, such as vehicle bodies, radiators orelectrical wound goods, and even without optimum—especiallycomplete—elimination of the shadow zones with actinic radiation, theyproduce coatings, adhesive films, and seals whose profile of performanceproperties is at least equal to that of the coatings, adhesive films,and seals outside the shadow zones. As a result, the coatings, adhesivefilms and seals in the shadow zones are also no longer readily damagedby mechanical and/or chemical attack, as may occur, for example, whenfurther components of motor vehicles are installed in the coated bodies.

Accordingly, the primed or unprimed substrates which are commonlyemployed in the technological fields set out above and which are coatedwith at least one coating of the invention, bonded with at least oneadhesive film of the invention and/or sealed with at least one seal ofthe invention combine a particularly advantageous profile of performanceproperties with a particularly long service life, so making themparticularly attractive economically.

EXAMPLES Preparation Example 1

The Preparation of an Emulsifier

A suitable reaction vessel fitted with three feed vessels, stirrer,reflux condenser, and oil heating, was charged with 52.56 parts byweight of deionized water and this initial charge was heated to 90°Celsius. Thereafter, at this temperature, three separate feed streamswere metered in to the initial charge in parallel and at a uniform rate.The first feed stream consisted of 10.18 parts by weight of acrylicacid, 18.35 parts by weight of methyl methacrylate, and 1.49 parts byweight of diphenyl ethylene. The second feed stream consisted of 9.9parts by weight of a 25% strength by weight ammonia solution in water.The third feed stream consisted of a solution of 2.25 parts by weight ofammonium peroxodisulfate in 5.25 parts by weight of deionized water. Thefirst and second feed streams were metered in over the course of onehour. The third feed stream was metered in over the course of 1.25hours. After the end of the addition, polymerization was continued forfour hours. During this time the temperature of the reaction mixture wasslowly reduced. The result was a dispersion of the emulsifier having asolids content of 33% by weight. The aqueous solution of the emulsifierhad a surface tension of 50 mN/m at the critical micelle concentration.

Example 1

The Preparation of a Powder Slurry of the Invention

Three heatable melt containers were connected via metering pumps to astatic Sulzer mixer (empty volume: 0.0463 liter). The exit of the mixerwas connected to a toothed-ring dispersing unit (K-Generator fromKinematica AG, Lucerne, Switzerland) into which a continuous aqueousphase was metered in parallel to the disperse phase (the mixture of thethree melts).

The first melt container contained a mixture of

-   -   95.1% by weight of a polyacrylate resin containing epoxide        groups, with an epoxide equivalent weight of 550 g/mol,    -   2.5% by weight of Tinuvin® CGL 1545 (commercial UV absorber from        Ciba Specialty Chemicals),    -   1.3% by weight of Tinuvin® 123 (commercial reversible        free-radical scavenger, HALS, from Ciba Specialty Chemicals),    -   0.3% by weight of Irgafos® P-EPQ (commercial antioxidant from        Ciba Specialty Chemicals),    -   0.8% by weight Troy® EX 542 (commercial benzoin-containing        devolatilizer from Troy, USA).

The melt was pumped into the mixer at 152° C. and a mass flow rate of 34kg/h. Its disperse phase fraction was 73.6% by weight.

The second melt container contained dodecanedioic acid, which at atemperature of 154° C. was pumped into the mixer at a mass flow rate of7.2 kg/h. Its disperse phase fraction was 16.2% by weight.

The third melt container contained a 3,5-dimethyl-pyrazole-blockedpolyisocyanate based on isophorone diisocyanate, having an NCO contentof 15.5% by weight, which at a temperature of 134° C. was pumped intothe mixer at a mass flow rate of 5.0 kg/h. Its disperse phase fractionwas 10.8% by weight.

After a residence time of 3.5 s, the melt entered the chamber of thetoothed-ring dispersing unit.

From a further feed vessel the continuous aqueous phase comprising58.25% by weight deionized water, 2.9% by weight emulsifier dispersionfrom Preparation Example 1 and 38.85% by weight TiO₂ pigment was meteredat a mass flow rate of 128.6 kg/h in parallel to the metering of themelt.

The rotary speed of the toothed-ring dispersing unit was 9000 rpm.

After leaving the toothed-ring dispersing unit the resulting emulsioncooled rapidly using a pipe cooler. The resulting powder slurry of theinvention had a z-average particle size of 8.5 μm (measured using theMalvern laser diffraction instrument).

The powder slurry of the invention was fully sedimentation-stable andhad outstanding transport and application properties. It gave smooth,glossy, scratch-resistant, flexible, hard, and chemical-resistantcoatings, especially primer-surfacer coats, basecoat, solid-colortopcoats, and combination effect coats. In multicoat systems, thecoatings displayed outstanding intercoat adhesion. Despite acomparatively low pigment content, they had an outstanding overallappearance.

Moreover, the powder slurry of the invention was outstandingly suitablefor the preparation of powder coating materials.

1. A process for preparing a pigmented powder coating suspension(pigmented powder slurry) by melt emulsification comprising (1) mixingat least two liquid components said components comprising a binder meltand a crosslinking agent melt, in a static mixer to give a liquidmixture, (2) emulsifying the liquid mixture in an aqueous medium in adispersing unit to give an aqueous emulsion of liquid particles, and (3)cooling the emulsion so that a suspension of dimensionally stableparticles is formed, wherein said aqueous medium comprises a suspensionof at least one pigment and wherein the binder and crosslinker are solidat room temperature and the melt of each is obtained by heating saidbinder and crosslinker to temperatures between 50° C. and 250° C. andsaid coating is curable by one of physically, thermally, or with actinicradiation, or thermally and with actinic radiation and upon curing saidcoating provides corrosion resistance, adhesion and absorption ofmechanical energy.
 2. The process of claim 1 further comprising applyingthe slurry to one of a motor vehicle body, a motor vehicle part, abuilding, a door, a window, furniture, a part, a coil, a container, anelectrical component, or a white good.
 3. The process of claim 1,wherein the residence time of the liquid components in the static mixeris from 0.5 to 20 seconds.
 4. The process of claim 1, wherein thedispersing unit is an inline dissolver.
 5. The process of claim 1,wherein the dispersing unit is an inline dissolver comprising atoothed-ring dispersing unit comprising at least one cylindricalarrangement of at least two comminutor rings (stator and rotor) that areseated on holders, are in mutual embrace, and are rotatable in oppositedirections relative to one another, the working gap produced by therelative movement between stator and rotor having walls that extendnonparallelwise with respect to one another.
 6. The process of claim 1,wherein the residence time of the liquid and the aqueous medium in thedispersing unit is from 0.5 to 20 seconds.